The focus of our work is the development of risk assessments and analyses that support risk management policy decisions for CBER products. The projects cut across many of the areas of CBER including blood and blood products, vaccines, and cell, tissue and gene therapies. The basis of our work is the generation of computer simulation models using statistical techniques such as Monte Carlo analyses to mathematically approximate the key processes to obtain better estimates of risk and to understand the uncertainty associated with these risks. The models are used to evaluate various risk management and risk reductions strategies to identify the most optimal approaches. These powerful techniques have been applied to assessments of risk for TSE agents in blood and tissue products. We have also used modeling approaches to evaluate the impact of rapid nationwide smallpox vaccination on the U.S. blood supply and to evaluate optimal strategies for maintaining the blood supply during a mass vaccination campaign. There are a number of projects currently in the development stages. A project currently underway will generate a computer model that can by used by CBER review staff to evaluate the risks and benefits of HIV vaccines with various characteristics (e.g. limited efficacy, etc.). We are also using modeling techniques to estimate the risk of severe adverse events that might arise from retroviral vector-mediated gene therapies and hope to use the model to identify risk reduction strategies.